Method for the manufacture of acid resistant fluxes for enamel colors



Patented Sept. 19, 1933 mm, S AT S 7 METHOD FOR THE MANUFACTURE .oFAIcinf" I 1 I.

. RESISTANT ,F X s; 1103 ,IEVNA'ME L..

' COLORS Theobject of this invention is the production -of vitrifiable enamel colors, and more especially to the productionof ,those colors which will give. when fused to objects such as ceramic articles 5 and metals, a surface or glaze which is highly reis ant o. a i .1 'i a In the known method; of making acid resistant vitrifiable colors; comparatively large quantities of silica, and silicates are used in the flux. ,Be-

10 cause-of the high melting point of thesilica compounds, it has been customary to add. certain quantities of boric acid in order to lower the melting point of the flux. However, these additions of boric acid lower theacid resisting properties of the fused product. An additional disadvantage of the known acid resisting vitrifiable colors is that they possess less gloss and brilliance of appearance than those colors which are considered as non-acid resistant.

It has now been found that vitrified colors of high acid resistance and having a brilliant gloss may be produced by the addition of a lithium compound to a silicate flux.

The lithium is added either in the form of a 1 5 silicate or as a substance which will be converted to the silicate when the flux mixture is melted. Lithium silicate, for example, can be prepared by fusing together lithium carbonate and silicic acid (silica) and this product canthen be fused in any proportions desired. The ingredients which react to form lithium silicate, such as lithium carbonate and silica, may be mixed before fusing with the other constituents of the flux, such as red lead, and this mixture then fused together. Satisfactory fluxes have been made from red lead, lithium oxide, and silica. However, the fluxes of this invention may contain other components, such as potassium oxide, po-

the eutectic just described, is fused with a lead compound such as red lead. When using lithium and silica in the proportions in which they are 155 present in the above described product, obtained pared vr q I f qn ith lted l.

with other fluxing ingredients, such as red lead,.

106.5 parts by weight ofchromic oxide, 128 to by fusing together 2l93. parts; of rememb r; bonate and 88.1 partsof silicic acid, aboutl2 parts ,of red lead can be fu'sed; with about1l20 to 240 partsby weight of the lithiumsilicate -silicic acidmelt.

' I prefer to' use lead com pounjdsin the proper tion of 228 parts, by weight-of red lead'or its equivalent with about 180 toflOFl parts by weight of the lithium oxide-:silicic iaci d eutectic described above, since the fluxesand the colorsob tained therefrom are exceptionally acid resistant andigiv e a very brilliant gloss to the vitrified col;

orsarfThie eutectic silicatecompositions can be squads q t aa e re a es bxf ll 'n tits ponents'in the presence: of the lead compounds. I They may contain for instance lithium-oxide and silica in the following proportions:

88 parts by weight SiO and712 parts by weight L 20 parts by we ght S10 and '20 parts by weight. L1 0 58 parts by weight SiO and 42 parts'by. weight L1 0 In addition to lead, silica and lithium, the fluxes cancontain other constituents, For ex.- ample, a satisfactory flux containing potassium has been prepared having the followingcomposition in molecular percent;

The final vitrifiablecolors are obtained in the f usual manner by mixing coloring bodies or oxides with the lithium fluxes described above and milling or fusing the mixture; 10 to 30 parts of pig-v ments'may be used with parts of flux. The addition of the coloring -matter has very little effect on the acid resisting properties of the f A few examples will serve to illustrate my inven-' tion, as follows:' a r Erample I A reddish-brown pigment was first prepared by thoroughly mixing and then calcining 30.4.t0 100 148 parts of iron oxide and 81 to 162 parts by weight of zinc oxide. .20 parts of this pigment were thoroughly ground up with 100 parts of a. flux which was obtained by fusing together'228, parts by weight of red. lead, 60 parts of lithium carbonate, and parts by weight of silica.

Example II y 228 parts by weight of red'lead were mixed and fused with204 parts by weight of lithium the same time lowered the resistance of the flux I or color to acid and diminished the gloss of the silicate which was obtained by melting together appearance and'great purity of color tone. The" vitrifiable colors have a high silica content and are more resistant to acids than the known colors having the'same silica content. This invention H eliminates the use of boric acid which was previously used to lower the melting point of a flux or color having a relatively highfsilica content and which not only lowered the melting point, but at What I claim is: I, 1 A method for the manufacture of acid resistant fluxes for enamel colors which are free from boric acid which comprises'fusing a lead compound with such proportions of a lithium compound and silica as to produce when fused a eutectic composition of lithium oxide and'silica.

acid resistant vitrifiable colorwhich is free from boric acid comprising a fused mixture of an enamel pigment and a flux which contains lithium silicate and lead oxide. 7 30.

3. An acid resistant vitrifiable color which is free from boric acid comprising a fused mixture of an enamel pigment and a flux which contains lead oxide and a eutectic composition of lithium oxide and silica, said eutectic composition consistingof lithium oxide and silica in the proporand-180 parts of'silica. r

tions in which they are obtained by fusing together about 30v parts by weight of lithium carbonate and 88 parts of silica.

4. An acid resistant vitrifiable color which is free from boric acid comprising .a fused mixture of an enamel pigment and a fiux comprising 228 parts of red lead'and about 180 to 204 parts by weight of a lithium silicate composition. I

55. An acid resistant vitrifiable color which is free from boric acid comprising a fused mixture of an enamel pigmenta-nd a flux consisting of 228 parts by weight of red lead and about 180 to 204. parts by weight of a lithium oxide silica eu- 'tectic composition, obtained by fusing together about 30 parts of lithium carbonate and 38 parts of silica. y 7

fipAnacid resistant vitrifiable color which is free. from boric acid comprising a fused mixture of about Y, 20 parts of a calcined mixture of 30 to 106 parts by weight of chromic oxide, 128 to 9 148parts of iron o'xide and .81 :to 162'pa'rts of zinc oxide and 'parts of a flux'consisting of the fused mixture of 228 parts by weight of red lead, 60 parts by weightof lithium carbonate 7. An acid resistant flux for vitrifiable colors which is free from boric acid consisting of 228 parts by weight of red'lead and, about 180 to 204 parts by weight of a lithium oxide-silica eutectic composition in which the lithium oxide and silca I are present in the proportion obtain'edwhenfusing together about30 parts oflithiumcarbonate and 88 parts of silica. I

' HERMANN EISENLOHR. l

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